When sheets of rubberized fabric are being assembled, such as during the building of tires, it is necessary to bring the tacky surfaces of said sheets into intimate contact and to work out entrained air by rolling the surface with a narrow rolling device commonly referred to as a stitcher. A stitching apparatus of the foregoing type is illustrated in Applicant's prior U.S. Pat. No. 4,057,455 dated Nov. 8, 1977.
The rolling devices or stitcher wheels are normally rounded at the point of contact with the rubberized sheets so that with the stitcher wheels engaging said sheets and moving outwardly in opposite directions toward the tire edge there remains a central area that is not engaged by said wheels. The prior art does teach the concept of multi-wheel stitchers but such devices are of the static type having three or more wheels. The patents to Thorpe et al U.S. Pat. No. 1,721,842 dated July 23, 1929 and Caretta U.S. Pat. No. 3,819,449 dated June 25, 1974 and Takasuge U.S. Pat. No. 4,004,961 dated Jan. 25, 1977 are illustrative of such prior art devices. In many instances the multi-wheel stitchers of the prior art are arranged to progressively engage the tread component of a tire with the various wheels and such engagement tends to produce trapped air pockets due to such intermittent engagement. In certain prior devices the stitcher wheels are not capable of stitching tire components other than the tread portion.
In an attempt to overcome the shortcomings of known stitcher assemblies, and particularly as concerns the center portion or area of a tire, specifications were devised calling for a manual stitching operation at the center section of a tire. Such a concept is not only time consuming, but it is a laborious task that is not uniform at all times, especially as concerns the degree of manual pressure applied, thus, quite often a poorly produced stitchout is obtained at the center portion or area of the tire.